Facing the challenges of grid stability brought by the large-scale access of new energy to the grid, as one of the important means of frequency regulation of the grid, the doubly-fed pumped-storage units (DFPSU) have great practical significance in the study of the joint frequency regulation strategy with the thermal power unit (TPU). In order to reduce the frequency regulation pressure on the grid caused by the large-scale entry of new energy sources, this paper proposes a joint frequency regulation strategy for the TPU and DFPSU. Based on establishing the optimal scheduling model of the system, taking into account the minimum total operating cost and the optimal time as goals, the chaotic particle swarm optimization (CPSO) is proposed to solve the model. Finally, through MATLAB simulation, the relevant examples are studied and analyzed, and the simulation results verify that the joint frequency regulation strategy in this paper can effectively improve the frequency regulation performance of the unit and the operation economy is good.

Arc suppression and resonance elimination device was used more and more widely in distribution power systems. The performance for limiting overvoltage and eliminating arc are better than arc suppression coil. But when the device not work properly,it would cause more great risk on the safe of the distribution network. It was analysed that an event of power failure of pair circuits distribution network installed with arc suppression and resonance elimination device. As an example, the simulation model was established with PSCAD software, and the working mechanism of the device was discussed. The overvoltage risk of the distribution system for water supply pump station was analysed. According to the analysing results, it is proposed that routine maintenance method and typical configuration of the device.